1. Technical Field
The present invention is related generally to the detection of polypeptides and nucleic acids separated by chromatographic or electrophoretic procedures. More particularly, the present invention is related to a unique silver stain and a simple, rapid and quantitative method for detecting nucleic acids and proteins on commonly available membranes or thin layer plates and the like employed as supporting and separation medium using the silver stain of the present invention.
2. State of the Art
Silver stains for the detection of proteins such as described in U.S. Pat. Nos. 4,405,720 and 4,555,490 are more sensitive than the organic stains such as Coomassie blue or amido black. However, the prior art Holman & Stern, Chartered Folio P49616 silver stains for the detection of proteins on membranes either result in relatively dense background staining (Merril et al., Electrophoresis 5:289-297, 1984), or require considerable time to develop. For instance, the method of Yuen et al., Anal Biochem 126:398-402 (1982) requires 45 minutes of manipulations in addition to an overnight reaction. Background staining problems have also limited the use of stains which employ colloidal gold and silver, restricting their use to nitrocellulose membranes. Furthermore, the colloidal gold and silver stains require 4 and 2 hour incubations, respectively (Moeremans et al., Anal Biochem. 145:315-321, 1985). Additionally, the prior art silver stains produce a combination of negative and positive images which make quantitation of the polypeptide difficult.